1. Field of the Invention
The invention relates to a self-boosting disk brake. The disk brake is intended in particular as a wheel brake of a motor vehicle.
2. Description of the Prior Art
A disk brake of this kind is known from German Patent Disclosure DE 103 02 516 A1. The known disk brake has a brake caliper, in which a friction brake lining is disposed on one side of a brake disk and can be pressed for brake actuation against the brake disk by an actuation device.
As a self-boosting device, the known disk brake has a wedge mechanism, with a wedge face extending obliquely at a wedge angle to the brake disk, on which face the friction brake lining is braced and along which the friction brake lining is movable. When the rotating brake disk exerts a frictional force on the friction brake lining that is pressed against it when the brake is actuated, the bracing of the friction brake lining at the wedge angle on the wedge face of the wedge mechanism effects a supporting force on the friction brake lining that is oriented perpendicular to the wedge face. One component of the supporting force acts on the friction brake lining perpendicular to the brake disk. This component of the supporting force of the wedge mechanism is a contact pressure, which presses the friction brake lining against the brake disk. The contact pressure effected by the wedge mechanism acts on the friction brake lining in addition to an actuation force that exerted by the actuation device and that together with the contact pressure exerts a tensing force, with which the friction brake lining is pressed against the brake disk. In the manner described, the wedge mechanism converts the frictional force, exerted by the rotating brake disk on the friction brake lining that is pressed against it when the disk brake is actuated, into a contact pressure that presses the friction brake lining against the brake disk. As a result of the contact pressure exerted on the friction brake lining in addition to the actuation force, a braking force of the disk brake is increased; the wedge mechanism effects self-boosting of the disk brake.
As the actuation device, the known disk brake selectively contemplates an electromechanical actuation device with an electric motor, optionally a step-down gear, and a spindle drive, or in other words a screw drive, or selectively a hydraulic actuation device with a hydraulic piston. The actuation device is secured to the brake caliper on the same side as the friction brake lining and on the same side as the wedge mechanism that forms the self-boosting device.
The wedge mechanism of the known disk brake acts on the brake caliper in the sense of spreading it open. Since in practice the brake caliper is not absolutely rigid, the wedge mechanism effects an elastic spreading open of the brake caliper, which lengthens an actuation travel of the actuation device. Actuation energy necessary for brake actuation is increased accordingly.